MCM 5 Post-Construction Stormwater Management

Infiltration basin protected by silt fence during construction

Introduction

Paved surfaces exacerbate the negative impacts to stormwater, including increasing the stormwater discharge volume and pollutants in stormwater. Managing stormwater onsite post-construction is the more effective way to mitigate these impacts. Minimum Control Measure (MCM) 5 of the municipal separate storm sewer system (MS4) General Permit requires permittees to have and enforce a post-construction stormwater management program that prevents or reduces stormwater pollution in new- and re- development projects.

MS4 General Permit requirements for MCM 5

The post-construction stormwater management program should include:

• A regulatory mechanism that requires proposers of construction activity to submit site plans with post-construction stormwater management best management practices (BMPs).
• A regulatory mechanism that requires the use of green infrastructure.
• A regulatory mechanism that specifies that there will be no net increase in stormwater volume, total suspended solids (TSS), and total phosphorus (TP) from new development projects; and a net decrease in volume, TSS, and TP for redevelopment projects.
• A regulatory mechanism that prohibits infiltration in certain situations, and restricts it in others, as described here.
• Mitigation provisions if TSS and TP cannot be managed onsite.
• A long term maintenance agreement for private structural stormwater BMPs.
• Site plan review procedures to ensure the post-construction stormwater management is in accordance with the regulatory mechanism.
• All documentation described here.

Resources

Click on the blue links above in the "MS4 General Permit requirements" section to jump to the referenced section or page. Links to specific resources related to MCM 5 are listed below.

Fact sheets and guidance documents

Fact sheets and guidance documents should provide background information and tips to inform your approach to implementing MCM 5 - Post-Construction Stormwater Management.

• EPA MCM 5 guidance - EPA's guidance and suggested BMPs for an effective post-construction stormwater management program
• MPCA Minimal Impact Design Standards guidance - MPCA fact sheet on Minimal Impact Design Standards (MIDS) and how communities can adopt the MIDS requirements
• MPCA MCM 5 Technical Support guidance - MPCA guide on how to comply with the 2013 MS4 General Permit MCM 5 post-construction stormwater management requirements
• "Model" MCM 4 and MCM 5 regulatory mechanism guidance (wq-strm4-98)
• Minimal impact design standards: Community assistance package (p-gen3-16)

Model language

Fill in the blanks and adopt ordinance or long-term maintenance agreement language that meets the regulatory mechanism requirements for MCM 5 - Post-Construction Stormwater Management.

• Minimal Impact Design Standards (MIDS) Community Assistance Package - MPCA's guidance and model ordinance language to implement low impact design within your community
• Long-term maintenance agreement model - MPCA's model long-term maintenance agreement template for general projects
• Long-term maintenance agreement model - MPCA's model long-term maintenance agreement template for rain gardens
• Long-term maintenance agreement model - MPCA's model long-term maintenance agreement template for stormwater quality treatment facilities
• Long-term maintenance agreement model - Middle St. Croix Watershed Management Organization's long-term maintenance agreement template
• Long-term maintenance agreement model - Cottage Grove's long-term maintenance agreement template

Example ordinances

• The City of Bayport's Stormwater Ordinance - City of Bayport's ordinance that adopts MIDS
• West Lakeland Township's Stormwater Ordinance - West Lakeland Townships's ordinance that adopts MIDS
• City of Lakeland's Stormwater Management Ordinance - City of Lakeland's ordinance that adopts MIDS

Documentation and tracking templates

Documentation and tracking templates are examples that local stormwater staff are currently using to meet the MS4 General Permit requirements for MCM 5 - Post-Construction Stormwater Management.

• Enforcement action documentation template - MPCA's template for documenting all enforcement actions used to compel compliance with your regulatory mechanisms
• Documentation that MS4 staff should retain - List of all the documentation requirements (what information to keep, how long to keep it, level of detail to keep, etc.) for compliance with the MS4 permit

Checklists

Below are methods that local stormwater staff are currently using to meet the site plan review documentation Post-Construction Stormwater Management requirements in the MS4 General Permit for MCM 5 - Post-Construction Stormwater Management.

• Site plan review checklist - MPCA's site plan review checklist
• Site plan review checklist - City of Cloquet's site plan review checklist
• Site plan review checklist - City of Hutchinson's site plan review checklist
• Site plan review checklist - City of Rice Lake's site plan review checklist

Example Procedures

Example procedures are those that local stormwater staff are currently using to meet the MS4 PART III.STORMWATER POLLUTION PREVENTION PROGRAM (SWPPP)#5. Post-Construction Stormwater Management| MS4 General Permit requirements for MCM 5 - Post-Construction Stormwater Management.

• Site plan review procedure - City of Elk River's site plan review procedure
• Site plan review procedure - City of Cloquet's site plan review procedure
• ERP - post construction stormwater management - City of Rice Lake's enforcement response procedure for observed violations with post-construction stormwater management requirements

Post-construction stormwater management

The information in this section provides MS4 permittees with tools they can use to meet MCM 5, which addresses post-construction stormwater management.

• Training programs and print materials for Minimum Control Measure (MCM) 5